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By Corby G. Anderson

Antimony has been utilized by mankind for thousands of years. However, due to recent environmental concerns, antimony is often considered to be an impurity element, Since antimnoy is commonly found in precious metal refractory ore bodies, extraction is essential. The Sunshine Mine in Kellogg, Idaho has recovered antimony from its precious metal tetrahedrite deposits since the 1940's. A plant was initially constructed as a primary antimony source during World War II. This facility also decreased the downstream smelting penalty for the silver copper-lead concentrate and provided an industrial commodity from a potential environmental nuisance.' This paper describes the Sunshine antimony processing- facility. Specifically, the relevant process chemistries involved in concentrate leaching, metal electrowinning, and sodium antimonate production will be discussed. In addition, ongoing areas of research to improve unit operations and treatments implemented to meet environmental' discharge requirements will be covered.

Jan 1, 1992

By E. J. Roberts

F. C. Bond (Allis-Chalmers Mfg. Corp., Milwaukee) —This paper considers comminution as a first order process, with the reduction rate depending directly upon the amount of oversize material present. The data show that other factors should be taken into account, and it is possible that in time these may be evaluated as simultaneous or consecutive reactions: Development of the theory of comminution has been retarded for many years by the assumption that surface area measurements constitute the sine qua non of the work done in crushing and grinding, and it is encouraging to note the belated growth of other ideas. In the Abstract the term "net power" should be changed to "net energy." Throughout the paper the term "hp per ton" should be changed to "hp hrs per ton", or "hp hr t." The term "Probability Theory" in the title does not seem appropriate, since it is not clear how the probability theory is used in developing the ideas in the paper. There seems to be a contradiction between the large calculated advantages of closed circuit operation and the statement following that the closed circuit test results showed no significant change in grinding behavior, when compared with the batch grind curves. Tables I and II show that between 75 pct and 50 pct solids the energy input required decreases with increasing moisture content and may indicate the advisability of grinding at higher dilutions in certain cases. The calculation of the hp-hr per ton factor indicates an input in the laboratory mill of only 7.32 gross hp per ton of balls; this casts some doubt upon the accuracy of the factor used, since the power input in commercial mills at 80 pct critical speed is customarily much higher. The tests show that within fairly wide limits the amount of ore in the laboratory mill may be varied and a product of constant fineness obtained, provided that the grinding time is varied in the same proportion. This has often been assumed, and confirmation by actual testing is of value. The Cavg corrections for differences between the plant and laboratory size distributions do not seem very satisfactory, since in many cases the plant/laboratory ratio is farther from unity after correction than before. The following equation has been derived from the data in Table VI: Relative Energy (log new ball diam in in. + 0.410) Input = --------------—--------------- from which the relative energy inputs for balls of different sizes can be calculated and compared. The relative energy input is unity for balls of 2.715 in. diam. The equation indicates that the work accomplished by a ton of grinding balls per unit of energy input is roughly proportional to the square root of the total ball surface area; provided, of course, that the balls are sufficiently large to break the material. The data in support of this statement are admittedly meager, but are fairly consistent when plotted. The relative grindability values listed in Table VI for 200 mesh multiplied by 4/5 apparently correspond approximately to the A-C grindability at 200 mesh.' It would seem that for open circuit tests comparable accuracy could be obtained much more simply by the old method' of plotting the test grind, extending the mesh grinds to the left of zero time if necessary, and determining from the plot the equivalent time required to grind from the plant feed size to the plant product size, using the average of several mesh sizes. The en- ergy input value of one time interval could be determined by tests on materials of known grinding resistance, and this multiplied by the interval required should give the desired energy input value. The relative grindabilities would be the relative time intervals required for a specified feed and product size. When the plotted mesh size lines of a homogeneous material are extended to the left beyond zero time they meet at one point at zero pct passing. The horizontal distance of this point from zero time indicates the equivalent energy input required to prepare the mill feed. The author's results show that the closed circuit grinding tests give about the same K values as open circuit tests, from which he concludes that open circuit tests are satisfactory in many cases. The value of the closed circuit test is its ability accurately to predict energy requirements in closed circuit grinding for both homogeneous and heterogeneous materials. If the material is homogeneous, the open circuit test gives satisfactory results; but if the material contains appreciable fractions of hard and soft grinding ore, the open circuit tests will not be accurate because of the accumulation of hard grinding material in the circulating load. Since in most cases it is not possible to determine a priori whether the material contains hard and soft fractions, the closed circuit tests are preferable and more reliable. B. S. Crocker (Lake Shore Mines, Ontario)—Dr. Roberts probability theory of grinding is very similar to our log pct reduced vs. log tonnage method of plotting and evaluating grinding tests at Lake Shore. However, although we both seem to start at the same point we finish with different end results. Shortly after publishing our grinding paper (referred to by Dr. Roberts) in 1939, we did pursue the subject of the "constant pct reduction in the pct +28 micron material for each constant interval of time. We ran innumerable tonnage tests on the plant ball mills, rod mills, tube mills with 11/4 and 3/4 balls, and lastly pebble mills, with tonnage variations from 180 tons per day to 950 tons per day. We found that when we plotted the log of the tonnage against the log of the pct reduced of any reliable mesh, we had a straight line up until 90 pct of the mesh is reduced. We have also tested this in our 12-in. laboratory mill with the same results. We have used this method of evaluating grinds for the past 8 years and developed the recent four stage pebble plant on this basis. By pct reduced we mean the percentage of any given mesh that is reduced in one pass through a mill at a given tonnage (or time). For example, if the feed to a rod mill is 90 pct +35 mesh and the discharge at 500 tons per day is 54 pct +35, the pct reduced is 90 — 54/90 = 40 pct. If the feed had been 80 pct +35 the discharge would have been 48 pct +35 or pct re- duced 80-48/80 = 40 pct as long as the tonnage re- mained constant at 500 tons per day. Thus we can easily correct for normal variation of mill feeds. This log — log relationship derived from the tonnage tests of all our operating mills has proved of tremendous help in checking laboratory work and in designing alternate layouts or new plants. The difference between the log — log and the semi-log plot is only shown up when the extremes in tonnages are plotted. When the relationship between the pct reduced and the tonnage was first investigated, we used semilog

Jan 1, 1952

By M. Hao, S. Hu, X. Lyu, M. Lian, C. Anning, G. Yao, Z. Wang

The results revealed that the pozzolanic activity of the gold mine tailings and their main mineral phases improved by mechanical activation. Under the same activation conditions, the activated mica powders possessed the highest pozzolanic activity index, followed by the activated feldspar, and the activated quartz exhibited the lowest pozzolanic activity index. The addition of calcium oxide promoted the formation of amorphous C–(A)–S–H gel for all paste samples, and stratlingite and hydrotalcite were observed in calcium oxide activated mica paste. The addition of natural anhydrite promoted the formation of ettringite for the pastes of calcium oxide activated aluminosilicates materials (gold mine tailings, mica, and feldspar). Furthermore, the pozzolanic activity indexes of the mechanically activated gold mine tailings and their main mineral phases were tested to be qualified for use as supplementary cementitious material in cement. This paper provided an innovative approach for recycling gold mine tailings as supplementary cementitious materials in cement, which would be environmentally friendly and cost-effective. Keywords: Mechanical activation, gold mine tailings, supplementary cementitious material, hydration properties, pozzolanic activity

Jan 1, 2020

By Anna Franzkowiak, Dean Gregurek, Alfred Spanring, Angelika Ressler

In order to determine the most suitable refractory products and improve the lining lifetime for the diverse furnaces used in the nonferrous metal industry, corrosion tests are performed at RHI’s Technology Center. The practical facilities include the cup test, induction furnace, rotary kiln, and drip slag test described in this paper, which enable a comprehensive understanding of the chemo-thermal brick wear on a pilot scale. The corrosion trials are performed with actual slags generated during operations at a customer’s plant. To determine the highest influencing wear parameter, every single test is combined with a detailed mineralogical investigation and thermochemical calculations performed using FactSage. Based on the results, tailored refractory solutions for the nonferrous metal industry can be provided in combination with trials conducted at the customer’s site.

Jan 1, 2014

By Winfried Rosenstock, Carlos Orlandi

Along the Pacific West coast of Latin America there are several large operations of metal mining activities. To mention only a few: Chuquicamata in Northern Chile moving daily approximately one million t of copper ore and waste, Cerro Verde near Arequipa in Peru, or lanaccocia. Apart from the coal deposits in north-east Columbia it is mainly to deal with metal-mining, which has due to geographical reasons relatively high cash-cost. This sector of mining is traditionally severely depending on the world-market.There are reasons to believe that the world-market will remain on a low price level and some analysts predict that in general the price-level will continue on low basis for the next decade. The cash-cost factor becomes therefore even more important as it already is. The goldprice development during the year 1999 illuminates that market changes can quickly lead to a severe crisis which forces the shutdown of mines with cash-costs close to or above the present market price per ounce. The breakdown of the cash-cost shows, however, that there are ways to overcome even the crisis like it struck the low-grade open pit goldmines around the world. Especially hitherto the “Electronic Option” is the only solution as the possible reduction using advanced technology based on the application of electronic detonating systems and newly developed special ignition procedures. The electronic option will lead to tremendous cost reductions similar to the results of research operations Thiess Contractors, Brisbane, Australia have carried out in Australia in 1998 and 1999. The electronic option allows a comprehensive integration of side effects of the blasting process which in the past could not have been achieved so far. Electronic initiation can achieve secondary effects which have an additional and positive impact on the level of costs. Appropriate application can enhance the production of material which will reduce the primary crusher costs or even make a primary crusher operation obsolete.

Jan 1, 2000

By F. Nelson

RJB Mining is the largest coal producer in the UK. In January 1995 the Company acquired the Central North and Central South Regions of British Coal consisting of: ? 15 operating collieries -including capital equipment ? 2 care and maintenance mines ? 16 operating Opencast sites ? Interest in 26 prospective and 46 potential Opencast sites ? Approximately 417 million tonnes of proven and probable reserves and considerable mineral resource ? 9 million tonnes of coal stocks ? Long term contracts to supply approximately 90 million tonnes of coal to National Power and PowerGen to the period of 3 March 1998 ?Approximately 7,600 employees and 4,500 mining contractual labour. Up to the acquisition RJB Mining had the capacity to produce 14 million tonnes of saleable output with an approximate 1,500 strong workforce.

Jan 1, 1998

"The characterisation of resources and description of variability across different ore domains is key to accurate prediction of probable metallurgical performance. Such characterisation testwork often has limited drill-core from which to work and this immediately confines the characterisation method to smallscale. For flotation feeds, the JKMSI (Mineral Separability Indicator) is being developed as a potential characterisation tool, building on earlier work by Chudacek, (1990), which used shaken test tubes, and was called the EMDEE device. In addition, the consistency of flotation recovery for specified size fractions has shown to be preserved, irrespective of the amount of material in that size fraction obtained by different milling conditions, so that the overall recovery can be estimated from knowing the particle size distribution (McIvor and Finch, 1991; Bazin et al, 1994, Runge, 2007 and Wightman et al, 2010) The JKMSI unit uses less than 10 g of material per test in narrowly sized classes and results to date have demonstrated the value of the test. This paper discusses the potential of the test by demonstrating the link between JKMSI performance and mineralogy of five different ores from Laguna Seca, Escondida Minera Limitada as well as the correlation to plant scale performance obtained in an earlier survey (Coleman et al, 2006). Further work to tie down the proof of representatively of the small sample has been identified and is discussed and included in the paper. INTRODUCTIONSince the uptake of the flotation process at the turn of the twentieth century, small scale, laboratory methods have been sought to characterise flotation response. Although laboratory batch flotation tests are the most widely used method to evaluate reagents, characterise ore variability and obtain suitable model parameters using various scale up factors Runge (2101) other methods using less ore would be useful where ore samples were limited.A method using test tubes for testing ores’s flotation response to reagents was first developed by Ian Walk (Wark & Wark, 1935; Wark; 1938; Sutherland and Wark 1955). In these tests a 50 cc stoppered measuring cylinder served as a means for a qualitative experiment, the aeration being effected through violent shaking by hand. In these experiments about 10 g of mineral was ground by pestle and mortar under water after which the ground material was deslimed and adequately conditioned with the appropriate reagents."

Jan 1, 2013

By Y. Moriya, Y. Sadayoshi, Y. Nonogaki, Y. Takeda

"Preparation and growth processes of CaF2 on Si(111) and of . InxGa1-x,As islands on CaF2 by molecular beam epitaxy (MBE) are described. It was found that first of all the Si(111) surface treatment process to obtain the 7x7 reconstructed structure was necessary to ensure the cleanness of the surface and to grow a flat and high quality CaF2 on it. Growth of InxGa11-x,As islands on CaF2 was tried by droplet heteroepitaxy using the same MBE reactor. In,GaxGa1-xAs islands were successfully grown epitaxially, and the size and density of the islands dependent on the In composition were investigated.IntroductionThough semiconductor/semiconductor heterostructures are widely used for many device applications, small band off-sets of the conduction bands and the valence bands restrict the utilization of the intra-subband transitions to far-infrared regions. With InAs as the quantum well and fluorides as the barrier layers, we can design three-electronic-level systems in the infrared region, which is the low loss transmission window of the silica optical fibers. To realize those structures, we have grown InxGa1-xAs islands on CaF2 thin films that were epitaxially formed on Si(111) substrates by molecular beam epitaxy. By the droplet heteroepitaxy that we invented, the InxGa1-xAs islands with height of -10 nm have been obtained successfully. Optimum processing to obtain atomically smooth surfaces of Si and CaF2 and high quality InxGa1-xAs islands is reported.ExperimentsMBEMachineCaF2 was grown on Si(111) and InxGa1-xAs islands were grown on CaF2 successively by MBE. The MBE machine consisted of a growth (or reactor) chamber and a loading chamber. The reactor chamber was equipped with Ga, In, As and Er metal source cells and CaF2 and BaF2 source cells. Cell materials were P-BN for Ga, In and As metals, and were graphite for CaF 2, BaF 2 and Er to avoid reaction with BN cells. The electron gun and screen were attached to the reactor to observe the RHEED pattern during the substrate surface treatment and the growth of CaF2 and InxGa1-xAs islands. The substrate manipulator was designed to heat up the Si substrate up to 1,200°C for the surface cleaning. The QMS was also equipped to analyze the residual gas species in the reactor chamber. The base pressure of the reactor chamber was 2-5x10-11 Torr, being pumped by ion pump and the liquid nitrogen shroud"

Jan 1, 2000

Obtaining correct assays for gold determinations relies on the correct methods being chosen and the assayer being made aware of the mineralogy of the sample and its general origin. Usually when a geologist or metallurgist obtains "incorrect" gold assays the problem can be traced to poor communication between the geologist or metallurgist and the assayer.

Jan 1, 1986

By O. C. Ralston

Natural or artificial manganese dioxide of a grade pure enough to be satisfactory as depolarizer for dry cells has never been available in large supply simultaneously with being available in desired quality . The Second World War called for more of it than ever . A supply of natural material from the Gold Coast was ample for the war and was not completely exhausted . Whereas the crystal form of the manganese oxide was not recognized as a matter of importance until the war came , it is now known that gamma MnO2 is a desirable form and that pyrolusite , once thought acceptable , is not the best mineral . The following paper is a translation of an internal company report filed at the Bitterfeld office of the I. G. Farbenindustrie A.G. by Dr. Peter Marx in 1933 , just a year after G. W. Nichols had published in the Transactions of the American Electrochemical Society a study of making anodic manganese dioxide from solutions of manganous sulfate . The I. G. experiments were made to confirm the American work and were also extended to a larger scale . Only chemical purity was considered , and no mention is made of crystal form . The report adds to the knowledge submitted by Nichols but has not been previously available to the general public . Believing it of value to the United States industry , a translation has been made .

May 1, 1948

By G. M. Mason

History Due to its strong affinity for oxygen, aluminium as an element was isolated only after many other rarer metals had been prepared and studied. It was just over one hundred years ago that two scientists, Hans Christian Oersted and Friedrich Wohler, produced the first few pellets of aluminium and determined its physical properties. These early investigators used metallic potassium as a reducing agent. Later, St. Claire Deville, by using sodium instead of potassium, improved the yield in the reduction and produced some pounds of aluminium. From a figure of about $110 per pound in 1855, the price had fallen to about $4 per pound by 1886. In that year, a very important discovery was made independently by Charles Martin Hall in Oberlin , Ohio, and Paul . Heroult in France. Stated in its simplest terms, the discovery of Hall and Heroult was that aluminium could be produced by electrolyzing a solution of the oxide in molten cryolite. The application of the Hall-Heroult process made the metal immediately available in commercial quantities and, by 1900, the price had fallen to 23 cents per pound. The growth of the industry in the past fifty years is well known, and is outside the scope of this paper. It is, perhaps, not generally known that aluminium was first produced in Canada at Shawinigan Falls in 1901. Since that time, production has been continuous at one or more smelters in the Province of Quebec. The largest of these smelters, which is also the largest aluminium smelter in the world, is at Arvida, Quebec, on the Saguenay river. A large power potential and access to ocean shipping were the two principal reasons for the establishment of aluminium production facilities in the Saguenay district. It is interesting to note that the aluminium industry, as a large user of power, took an active part in the early industrial development at Niagara Falls and Shawinigan Falls, and is now repeating the process in the Saguenay valley.

Jan 1, 1949

By Howard C. Turnage, Dana T. Updyke

An evaluation was made of one of several improved underground communication systems sponsored by the U.S. Bureau of Mines. The system evaluated was installed in a typical metal/non-metal room and pillar mine and utilized UHF repeaters connected to a unique distributed antenna and passive reflector system which provided mine-wide communications. A microprocessor controlled data collection system was assembled and installed for the evaluation. Data consisting principally of times and durations of messages and identities of the originating transceivers was collected between February and August of 1982 (6 mos.). Analysis of the data shows that the principal benefits are reduction in time required for unscheduled maintenance and repair, enhancement of safety, and better coordination of production activities. A cost benefit analysis shows a net benefit over cost, although it is also concluded that the capacity of the system is greater than can be justified by current activity in the mine.

Jan 2, 1983

By M. K. Jain, Z. T. Xu, M. Bruhis, V. Hegedekatte

"Strain rate and temperature dependent deformation conditions are present during elevated temperature forming of aluminum and other metallic materials. While many constitutive laws have been proposed to represent such deformation conditions, a closer investigation often reveals their limited applicability in terms of fit to the experimental data, and interpolation within and extrapolation outside of the range of experimental stress-strain curves. This is often because material-specific primary deformation mechanisms of temperature-dependent strain and strain rate hardening are poorly captured. In the present work, the Voce-Kocks constitutive model based on mechanics of dislocations storage and annihilation has been found to be suitable for many metallic materials. The model was modified to include the effect of temperature dependent shear modulus. The modified model is then employed to represent the experimental data obtained from uniaxial tensile tests on AA7075-O sheet at elevated temperatures and strain rates. Also, hot gas bulging tests were conducted to verify the applicability of this model. Further, finite element simulation of the hot gas bulge test was performed by incorporating the model as a user material subroutine. Good general agreement was observed between the experimental and FE model predicted results. Some sources of discrepancy in the prediction are also discussed.INTRODUCTION There has been much interest in light-weighting of automobiles from automotive related industries to reduce overall carbon footprint and increase energy efficiency of the vehicles. Aluminum alloys, and especially the medium-strength 5xxx and 6xxx series alloys, have been the primary focus in the last 3 decades to reach the above environmental goals (Huo, Hou, Zhang, & Zhang, 2016) whereas aerospace industry has traditionally focused on high strength 7xxx series aluminum (Al-Zn-Mg-Cu) alloys for structural components (Deng, Yin, & Huang, 2011). Recently, there has been much interest in high strength 7xxx series aluminum as a replacement for heavier steel automotive structural parts such as A-pillar, B-pillar, side impact beams etc. (Harrison & Luckey, 2014). This is both interesting and challenging since the above aluminum structural parts will need to not only meet impact safety standards but also possess sufficient formability for manufacturing such complex parts. Since the formability of high strength 7xxx series materials is quite poor at room temperature, much interest has focused on improving both formability and final part strength via high rate hot stamping, in-die quenching, and subsequent artificial ageing process steps (Kumar & Ross, 2016)."

Jan 1, 2018

By T. D. Parris

At the Frood Mine of International Nickel, tests were begun in March 1966 to evaluate the use of low profile diesel Load- Haul-Dump equipment in cut-and-fill operations. In December 1966, this test was extended to drawpoint loading of caved ore at the Creighton Mine. The results of these tests conclusively demonstrated the effectiveness of this equipment in the operations at International Nickel. This paper describes the equipment used, the operation of the equipment, production data and operating details. Also discussed in the paper are other trackless equipment which works with the Load-Haul-Dump carrier. Production and Safety comparisons are made with the slusher method in bulk mining, giving the reasons for replacing the slushers at the mines of International Nickel Company of Canada, Limited, Ontario Division.

Jan 1, 1969

By M. H. Allan

SASKATCHEWAN POWER CORPORATION is a Provincial Crown Corporation responsible for the production transmission and distribution of electric power and natural gas in the Province of Saskatchewan. Through the electric power responsibility, we became interested in the coal reserves in Saskatchewan, which, although still somewhat of an "orphan fuel" in the early and mid 1950's, gave the promise of providing a low-cost source of energy for electric generation. Coal in Saskatchewan, a lignite with an "as-received" heating value of from 5000 to 6500 Btu's per lb and up to 40% moisture, was first recorded in 1853 . By the end of the 19th century, many small mines were in operation in the Estevan, Coronach and Shaunavon areas supplying local inhabitants with a cheap source of heat. These small mines, some of them prosperous, some of them not, continued operation right up to the late 1940's, when oil replaced coal in the market place. The year 1930, however, saw the introduction of the new technique of strip mining in the Estevan area. This technique revolutionized coal mining. It was now possible to use large machinery to uncover the coal and cast the overburden to one side instead of burrowing through thin seams of coal varying from 2 to 10 feet thick. The overburden cast aside by these large mechanical shovels, or later draglines, created heaps of spoil which at that time, during the depression, were a sure sign of prosperity and the welcome news that people had jobs. By the late 1940's, coal production had dropped off, but the spoil piles remained and were now labelled by some as "scars on the landscape", even though there had been some natural succession of grasses. In addition, some people had planted trees in experimental plots and even some aerial seeding had been done.

Jan 1, 1978

By T. A. Lang

The objective was to develop a Program Plan of analytical studies and tests for determining ( 1) the optimum installation tension of a coal mine roof bolt, (2) the most valid bolt support theory or theories, and ( 3) the most valid roof failure theory or theories. On this basis a comprehensive literature search was made and significant material dealing with coal mine roof behavior, roof bolting and roof support was collected, reviewed, classified and analyzed. Emphasis was given to the influence of rock reinforcement on the control of deformation, stress field modification and mine roof stability. An assessment was made of the effect of various parameters including bolt tension, bolt pattern and time of installation, on the effectiveness of rock reinforcement systems, and equations developed for bolt tension as a function of these parameters, and rock properties. From these studies, a major program plan of tests and studies was developed for verifying and validating the most tenable theories of roof behavior and roof support and for determining optimum bolt installation tension.

Jan 1, 1979

By Arthur Crowfoot

This paper describing t o concentrating practice of the Phelps Dodge Corporation, Morenci Branch, at Morenci, Ariz., is one of a series of articles on concentrating methods and posts being prepared by the Bureau of Mines. The Morenci concentrator, locally known as No. 6 concentrator, treats 5,000 dry tons of ore per 24-hour day by primary tabling followed by two stages of flotation treatment, at 48-mesh size and 65-mush size respectively.

Jan 1, 1931

By A Madera, R Watt

The Tampakan deposit is a strongly telescoped high-sulphidation-epithermal/ porphyry deposit pair which is hosted by a sequence of probable Pliocene age subaerial andesite flows. These host units lie on the western flank of a deeply dissected andesitic stratovolcano within the northernmost portion of the Sangihe Arc in southern Mindanao. The deposit was discovered by WMC geologists in 1992 and is currently undergoing resource evaluation. Preliminary resource estimations indicate a total inferred metal content of 12 million tonnes of copper metal and 16 million ounces of gold. Using a 0.2 per cent Cu cut-off grade, the deposit has a current mineral resource of approximately 2.5 billion tonnes with an estimated grade of 0.48 per cent copper. At a higher cut-off grade of 0.5 per cent Cu, the mineral resource is approximately 900 million tonnes with an estimated grade of 0.75 per cent copper. Mineralisation is open both to the west and at depth. The Tampakan district is centrally located with respect to a 100 km wide zone of left-lateral strike-slip deformation represented by the trans-Mindanao Cotabato Fault Zone. The district is transected by several WNW-striking wrench faults which represent strands of the regional Cotabato Fault Zone. High-sulphidation epithermal mineralisation within the Tampakan deposit is strongly controlled by NNE-trending faults which lie along a dilational orientation within the Pliocene stress field associated with the Cotabato strike-slip fault zone. The mineralisation is broadly hosted by a gently-dipping, tabular zone of partial to massive silicification which displays multi-phase brecciation, acid-leaching, related vuggy porosity and which is developed within a district-scale advanced-argillic and argillic lithocap exceeding 90 km 2 in area. High-sulphidation epithermal mineralisation is associated with a silica-pyrophyllite-dickite-alunite-diaspore¦sericite alteration assemblage which is transitional downward to sericite-chlorite alteration and relict potassic biotite-chlorite-magnetite-anhydrite alteration associated with pervasively developed but weakly mineralised porphyry quartz stockwork veins. The high-sulphidation mineralisation is dominated by disseminated, vein and vug-filling enargite-bornite-digenite-chalcocite-covellite ¦ molybdenite which has overprinted an earlier phase of porphyry copper stockwork veins associated with high-level porphyritic hornblende diorite stocks. The distribution of high-sulphidation alteration and mineralisation reflects strong stratigraphic and structural controls. The high-sulphidation mineralisation covers a surface area of approximately 1.6 km by 2.0 km and forms a tabular, flat-lying to gently-dipping body between 200 and 500 metres thick. It is intersected at RL-1200 m ASL (at surface) in the northern portion of the deposit and extends down to RL-600 m ASL at the southern end. The deposit has been diamond-drill tested to a depth of 400 - 500 metres where low-grade chalcopyrite-bornite-pyrite mineralisation is hosted by pervasive quartz stockwork veins. This deep-level mineralisation represents the outer portion of a porphyry Cu system hosted by both andesite flows and the uppermost portions of high-level hornblende diorite stocks. Deep drilling to test for higher tenor porphyry Cu mineralisation is planned.

Jan 1, 1999

By Roger L. Goin

Maintaining smooth haulage roads is a key to significant cost savings at Kennecott Copper Corp.'s Bing- ham Canyon copper mine, located near Salt Lake City, Utah. The truck operations section of the mine moves an estimated 300,000 tpd of waste plus some ore to maintain a balanced production cycle. A three-year truck replacement program has produced a dramatic new look in both size and capacity of the truck fleet. Currently there are 95 haulage trucks in the Bingham fleet with capacities up to 150 t. The trend towards the larger haulage units places greater importance on overall truck availability. The impact of a 150-t truck being out of service is far more critical than with the former 65 or 85-t units.

Jan 12, 1974

By Y. Chengxian

Many factors about the HIC (hydrogen-induced cracking) resistance of pipelines are discussed in this paper. The main factors that influence the ability of HIC are environmental and material factors. The chemical compositions, non-metal inclusions and microstructure are discussed in detail, while a group of tests on HIC resistance are done according to varying C, S, Mn and P contents in pipeline steels, different experiment time and different strength to the coupon. It is concluded that decreasing the amount of C and S can obtain good HIC resistance; the test time has an effect on the different microstructure of X70; microstructure is the most sensitive factor for the initiation processes of HIC.

Jan 1, 2005